喀斯特地区三种人工林土壤微生物群落结构特征

为揭示不同人工植被修复模式对喀斯特土壤微生物群落的影响,采用氯仿熏蒸提取法和磷脂脂肪酸(phospholipid fatty acid, PLFA)法研究人工构建的降香黄檀(Dalbergia odorifera)纯林(PDOP)、顶果木(Acrocarpus fraxinifolius)纯林(PAFP)、顶果木×降香黄檀混交林(MADP)对土壤微生物生物量及土壤微生物群落结构的影响。结果表明:(1)PDOP的土壤微生物生物量碳(MBC)和微生物生物量氮(MBN)含量显著高于PAFP和MADP,PAFP显著高于MADP。(2)三种人工林土壤真菌、丛枝菌根真菌和总PLFA含量无显著差异,但PDOP土壤细菌、放线菌、丛枝菌根真菌和总PLFA含量均高于PAFP和MADP,PAFP高于MADP。PDOP的土壤细菌、革兰氏阳性菌、革兰氏阴性菌、放线菌的PLFA含量显著高于MADP。MADP的真菌细菌比显著高于PDOP,但与PAFP无显著差异。(3)冗余分析表明,土壤阳离子交换量、pH和C:N是影响土壤微生物群落组成的最主要影响因子。从三种人工林的土壤微生物生物量及微生物群落结构来看,在喀斯特地区MADP并未显示出酸性土地区混交林提高土壤微生物生物量、改善土壤微生物群落结构的优势,但混交林的真菌细菌比最高,更有利于提高土壤生态系统的稳定性。

Characteristics of soil microbial community structure of three plantations in a karst region

In order to reveal the effects of different vegetation restoration modes on soil microbial communities in karst areas, this study took pure Dalbergia odorifera plantation(PDOP), pure Acrocarpus fraxinifolius plantation(PAFP)and their mixed plantation(MADP)as research subjects. The soil microbial biomass and microbial community structure of different plantations were analyzed by chloroform fumigation extraction method and phospholipid fatty acid(PLFA)method. The results were as follows:(1)The soil microbial biomass carbon(MBC)and microbial biomass nitrogen(MBN)contents of PDOP were significantly higher than those of PAFP and MADP, and that of PAFP was significantly higher than that of the MADP.(2)The contents of soil fungi, arbuscular mycorrhizal fungi(AMF)and total PLFA were not significantly different among the three plantations, but the contents of soil bacteria, actinomycetes, AMF and total PLFA in PDOP were higher than those in PAFP and MADP, and those in the PAFP were higher than those in MADP. The PLFA contents of bacteria, gram-positive bacteria, gram-negative bacteria and actinomycetes in PDOP were significantly higher than those in MADP. The ratio of fungi to bacteria in MADP was significantly higher than that in PDOP, but there were no significant differences between MADP and PAFP.(3)Redundancy analysis showed that soil cation exchange capacity, pH, and C:N were the most important factors affecting the functional group composition of soil microbial community. From the perspective of soil microbial biomass and microbial community structure of the three plantations, MADP in karst area don''t show the advantage of mixed forest in acid soil region to improve soil microbial community structure. However, the ratio of fungi to bacteria in the mixed plantation is the highest, which is more conducive to improving the stability of soil ecosystem.